A bent spring metal washer with a centrally located hole. It is designed to exert pressure axially when assembled in place.
NSN 5930-00-806-0146
NSN 2925-01-440-9912
NSN 4140-00-404-7092
NSN 6110-01-152-2840
NSN 6135-01-215-1245
NSN 6685-01-102-5994
NSN 5999-01-272-1535
NSN 5895-01-110-6737
NSN 5999-01-140-9665
NSN 6110-00-269-2696
NSN 5835-00-454-7239
NSN 6685-00-458-8001